Technical Field
The present disclosure relates to a microintegrated encapsulated MEMS sensor with mechanical decoupling, and to the manufacturing process thereof.
Description of the Related Art
As is known, microintegrated sensors obtained using MEMS (Micro-Electro-Mechanical-Systems) technology are spreading on the market, by virtue of their ever-increasing reliability, low costs, and very small dimensions. For instance, U.S. Pat. No. 6,131,466 describes a microintegrated MEMS pressure sensor of a piezoresistive type and the manufacturing process thereof. Another microintegrated pressure sensor, both of a piezoresistive type and of a capacitive type, is described in U.S. Pat. No. 8,173,513.
Microintegrated sensors generally have packages intended to protect the internal structures of the sensor from the external environment, for example to reduce disturbance due to temperature, humidity, particles or elements that prevent operation thereof or deteriorate performance thereof and/or to increase the mechanical strength thereof.
On the other hand, the manufacture of the package may cause stresses that may adversely affect the characteristics of performance, stability, and reliability of the sensor.
This is particularly true for sensors based upon piezoresistive characteristics of silicon, wherein the stresses are directly involved in the transduction mechanism. In these cases, then, an accurate design of the package is particularly desirable in order to limit the effects of stress caused by the package and by the assembly process, with particular attention as regards to the materials used and the effects arising during mechanical coupling between the sensor and the package.
For instance, the process of packaging by molding, which is the most commonly used in microelectronics, by virtue of its low costs and high throughput, may not be simply adopted, since it generates high stresses during resin injection and cooling.
The above undesirable effects become increasingly more important as the sizes of the dice and the packages increase and limit use of 3D packaging techniques.
In the past, various low-stress encapsulation solutions have been proposed and adopted. In some of these, the package comprises mechanical structures intended to also decouple the sensor from the surrounding environment. However, these solutions may also be improved.